6-Methyl-sulfanyl-4H-pyrimido[1,6-a]pyrimidin-4-one.

Reaction of 2-(methyl-sulfan-yl)pyrimidin-4-amine with the 5-(methoxy-vinyl-idene) derivative of Meldrum's acid and subsequent heating of the product in Dowtherm fluid yielded the title compound, C(8)H(7)N(3)OS, which was proven to contain a bicyclic 4H-pyrimido[1,6-a]pyrimidine system. All non-H atoms of the mol-ecule are coplanar within 0.15 Å. The bond-length distribution in the bicyclic core shows localization of the double bonds. The geometry of the intra-molecular S⋯O 1,5-contact [2.534 (2) Å] is consistent with the existence of an attractive inter-action.

Related literature

For the structure of a compound with a similar bicyclic carbon–nitro­gen core, see: Olomucki et al. (1984 ▶). For statistical studies of the geometry of S⋯O inter­actions, see: Rosenfield et al. (1977 ▶); Iwaoka et al. (2002 ▶).

Experimental

Crystal data

C8H7N3OS

M = 193.23

Monoclinic,

a = 9.7621 (8) Å

b = 4.1725 (3) Å

c = 20.4092 (16) Å

β = 100.106 (1)°

V = 818.42 (11) Å3

Z = 4

Mo Kα radiation

μ = 0.35 mm−1

T = 123 K

0.48 × 0.14 × 0.08 mm

Data collection

Bruker APEXII CCD diffractometer

Absorption correction: multi-scan (SADABS; Bruker, 2001 ▶) T min = 0.849, T max = 0.972

6497 measured reflections

1498 independent reflections

1333 reflections with I > 2σ(I)

R int = 0.022

Refinement

R[F 2 > 2σ(F 2)] = 0.035

wR(F 2) = 0.097

S = 1.13

1498 reflections

118 parameters

H-atom parameters constrained

Δρmax = 0.43 e Å−3

Δρmin = −0.19 e Å−3

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: SAINT (Bruker, 2004 ▶); data reduction: SAINT; program(s) used to solve structure: SIR2004 (Burla et al., 2005 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-32 (Farrugia, 1997 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809038562/rz2363sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809038562/rz2363Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

C8H7N3OS	F(000) = 400
Mr = 193.23	Dx = 1.568 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 4134 reflections
a = 9.7621 (8) Å	θ = 3.2–25.4°
b = 4.1725 (3) Å	µ = 0.35 mm−1
c = 20.4092 (16) Å	T = 123 K
β = 100.106 (1)°	Blade, brown
V = 818.42 (11) Å3	0.48 × 0.14 × 0.08 mm
Z = 4

Bruker APEXII CCD diffractometer	1498 independent reflections
Radiation source: fine-focus sealed tube	1333 reflections with I > 2σ(I)
graphite	Rint = 0.022
φ and ω scans	θmax = 25.4°, θmin = 2.1°
Absorption correction: multi-scan (SADABS; Bruker, 2001)	h = −11→11
Tmin = 0.849, Tmax = 0.972	k = −4→5
6497 measured reflections	l = −24→24

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.035	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.097	H-atom parameters constrained
S = 1.13	w = 1/[σ2(Fo2) + (0.045P)2 + 0.5615P] where P = (Fo2 + 2Fc2)/3
1498 reflections	(Δ/σ)max = 0.001
118 parameters	Δρmax = 0.43 e Å−3
0 restraints	Δρmin = −0.19 e Å−3

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

	x	y	z	Uiso*/Ueq
S1	0.56563 (5)	0.91748 (12)	0.81678 (2)	0.02069 (19)
O1	0.80408 (15)	0.9008 (4)	0.78390 (7)	0.0276 (4)
N1	0.59517 (17)	0.5753 (4)	0.92701 (8)	0.0203 (4)
N2	0.79659 (16)	0.5851 (4)	0.87620 (7)	0.0172 (4)
N3	0.99408 (17)	0.2689 (4)	0.92351 (8)	0.0238 (4)
C1	0.3990 (2)	0.9169 (5)	0.84302 (11)	0.0280 (5)
H1A	0.3333	1.0474	0.8123	0.042*
H1B	0.4089	1.0064	0.8880	0.042*
H1C	0.3642	0.6966	0.8431	0.042*
C2	0.65797 (19)	0.6714 (5)	0.87950 (9)	0.0183 (4)
C3	0.6652 (2)	0.3762 (5)	0.97497 (10)	0.0209 (4)
H3B	0.6193	0.3094	1.0100	0.025*
C4	0.7959 (2)	0.2700 (5)	0.97507 (9)	0.0203 (4)
H4A	0.8392	0.1284	1.0089	0.024*
C5	0.8678 (2)	0.3717 (5)	0.92427 (9)	0.0186 (4)
C6	1.0583 (2)	0.3766 (5)	0.87347 (11)	0.0254 (5)
H6A	1.1495	0.3010	0.8719	0.030*
C7	0.9993 (2)	0.5853 (5)	0.82589 (9)	0.0199 (4)
H7A	1.0506	0.6512	0.7927	0.024*
C8	0.8652 (2)	0.7063 (5)	0.82424 (9)	0.0219 (4)

	U11	U22	U33	U12	U13	U23
S1	0.0177 (3)	0.0225 (3)	0.0219 (3)	0.00111 (19)	0.0038 (2)	0.0028 (2)
O1	0.0237 (8)	0.0363 (9)	0.0241 (7)	0.0002 (7)	0.0079 (6)	0.0095 (7)
N1	0.0196 (8)	0.0199 (9)	0.0220 (8)	−0.0009 (7)	0.0053 (7)	−0.0002 (7)
N2	0.0184 (8)	0.0176 (8)	0.0164 (8)	−0.0021 (6)	0.0050 (6)	−0.0017 (6)
N3	0.0199 (8)	0.0240 (9)	0.0278 (9)	0.0015 (7)	0.0047 (7)	−0.0014 (8)
C1	0.0201 (11)	0.0335 (12)	0.0312 (11)	0.0032 (9)	0.0068 (9)	0.0059 (10)
C2	0.0169 (9)	0.0178 (9)	0.0201 (10)	−0.0015 (8)	0.0026 (8)	−0.0037 (8)
C3	0.0211 (10)	0.0232 (10)	0.0190 (10)	−0.0025 (8)	0.0052 (8)	0.0004 (8)
C4	0.0233 (10)	0.0189 (10)	0.0184 (10)	−0.0007 (8)	0.0026 (8)	0.0006 (8)
C5	0.0179 (10)	0.0173 (9)	0.0200 (10)	−0.0016 (8)	0.0022 (8)	−0.0041 (8)
C6	0.0180 (10)	0.0264 (11)	0.0326 (11)	−0.0005 (9)	0.0068 (9)	−0.0070 (9)
C7	0.0253 (11)	0.0186 (10)	0.0183 (10)	−0.0042 (8)	0.0108 (8)	−0.0040 (8)
C8	0.0234 (10)	0.0245 (11)	0.0186 (10)	−0.0066 (9)	0.0059 (8)	−0.0026 (9)

S1—C2	1.761 (2)	C1—H1B	0.9800
S1—C1	1.799 (2)	C1—H1C	0.9800
O1—C8	1.233 (2)	C3—C4	1.351 (3)
N1—C2	1.298 (3)	C3—H3B	0.9500
N1—C3	1.371 (3)	C4—C5	1.415 (3)
N2—C2	1.413 (2)	C4—H4A	0.9500
N2—C5	1.414 (2)	C6—C7	1.355 (3)
N2—C8	1.442 (2)	C6—H6A	0.9500
N3—C5	1.308 (3)	C7—C8	1.398 (3)
N3—C6	1.365 (3)	C7—H7A	0.9500
C1—H1A	0.9800
C2—S1—C1	99.03 (9)	N1—C3—H3B	118.2
C2—N1—C3	118.60 (17)	C3—C4—C5	119.37 (18)
C2—N2—C5	119.08 (16)	C3—C4—H4A	120.3
C2—N2—C8	121.20 (16)	C5—C4—H4A	120.3
C5—N2—C8	119.70 (16)	N3—C5—N2	123.26 (18)
C5—N3—C6	117.29 (18)	N3—C5—C4	119.98 (18)
S1—C1—H1A	109.5	N2—C5—C4	116.76 (17)
S1—C1—H1B	109.5	C7—C6—N3	123.66 (19)
H1A—C1—H1B	109.5	C7—C6—H6A	118.2
S1—C1—H1C	109.5	N3—C6—H6A	118.2
H1A—C1—H1C	109.5	C6—C7—C8	121.85 (18)
H1B—C1—H1C	109.5	C6—C7—H7A	119.1
N1—C2—N2	122.57 (17)	C8—C7—H7A	119.1
N1—C2—S1	118.33 (15)	O1—C8—C7	126.55 (18)
N2—C2—S1	119.10 (14)	O1—C8—N2	119.26 (18)
C4—C3—N1	123.53 (18)	C7—C8—N2	114.19 (17)
C4—C3—H3B	118.2